concrete5 Environment Information
# concrete5 Version
Core Version - 8.1.0
Version Installed - 8.1.0
Database Version - 20170123000000
# concrete5 Packages
Automatic Email Obfuscator (2.0.1), Background Image and Overlay (0.9.9), Cycle2 Slide Show (1.0.1), Webli Menu Maker (1.1.1)
# concrete5 Overrides
languages/es_PY/LC_MESSAGES/messages.mo, languages/es_PY/LC_MESSAGES, languages/es_PY, languages/nb_NO/LC_MESSAGES/messages.mo, languages/nb_NO/LC_MESSAGES, languages/nb_NO, languages/ru_RU/LC_MESSAGES/messages.mo, languages/ru_RU/LC_MESSAGES, languages/ru_RU, languages/it_IT/LC_MESSAGES/messages.mo, languages/it_IT/LC_MESSAGES, languages/it_IT, languages/da_DK/LC_MESSAGES/messages.mo, languages/da_DK/LC_MESSAGES, languages/da_DK, languages/en_GB/LC_MESSAGES/messages.mo, languages/en_GB/LC_MESSAGES, languages/en_GB, languages/nl_NL/LC_MESSAGES/messages.mo, languages/nl_NL/LC_MESSAGES, languages/nl_NL, languages/pt_BR/LC_MESSAGES/messages.mo, languages/pt_BR/LC_MESSAGES, languages/pt_BR, languages/ja_JP/LC_MESSAGES/messages.mo, languages/ja_JP/LC_MESSAGES, languages/ja_JP, languages/el_GR/LC_MESSAGES/messages.mo, languages/el_GR/LC_MESSAGES, languages/el_GR, languages/fi_FI/LC_MESSAGES/messages.mo, languages/fi_FI/LC_MESSAGES, languages/fi_FI, languages/de_DE/LC_MESSAGES/messages.mo, languages/de_DE/LC_MESSAGES, languages/de_DE, languages/es_PE/LC_MESSAGES/messages.mo, languages/es_PE/LC_MESSAGES, languages/es_PE, languages/sv_SE/LC_MESSAGES/messages.mo, languages/sv_SE/LC_MESSAGES, languages/sv_SE, languages/cs_CZ/LC_MESSAGES/messages.mo, languages/cs_CZ/LC_MESSAGES, languages/cs_CZ, themes/venus/page_theme.php, themes/venus/full.php, themes/venus/js/jquery.pagepiling.js, themes/venus/js/html5.js, themes/venus/js/animatefunctions.js, themes/venus/js/selectivizr-min.js, themes/venus/js/custom.js, themes/venus/js/wow.min.js, themes/venus/js, themes/venus/home.php, themes/venus/css/main.less, themes/venus/css/bootstrap-modified.css, themes/venus/css/skeleton.css, themes/venus/css, themes/venus/grids/skeleton_grid.php, themes/venus/grids, themes/venus/animate.css, themes/venus/description.txt, themes/venus/default.php, themes/venus/view.php, themes/venus/sass/skeleton.scss, themes/venus/sass/_normalize.scss, themes/venus/sass, themes/venus/main.css, themes/venus/elements/footer.php, themes/venus/elements/header.php, themes/venus/elements, themes/venus/New folder, themes/venus/thumbnail.png, themes/venus, languages/es_PY/LC_MESSAGES/messages.mo, languages/es_PY/LC_MESSAGES, languages/es_PY, languages/nb_NO/LC_MESSAGES/messages.mo, languages/nb_NO/LC_MESSAGES, languages/nb_NO, languages/ru_RU/LC_MESSAGES/messages.mo, languages/ru_RU/LC_MESSAGES, languages/ru_RU, languages/it_IT/LC_MESSAGES/messages.mo, languages/it_IT/LC_MESSAGES, languages/it_IT, languages/da_DK/LC_MESSAGES/messages.mo, languages/da_DK/LC_MESSAGES, languages/da_DK, languages/en_GB/LC_MESSAGES/messages.mo, languages/en_GB/LC_MESSAGES, languages/en_GB, languages/nl_NL/LC_MESSAGES/messages.mo, languages/nl_NL/LC_MESSAGES, languages/nl_NL, languages/pt_BR/LC_MESSAGES/messages.mo, languages/pt_BR/LC_MESSAGES, languages/pt_BR, languages/ja_JP/LC_MESSAGES/messages.mo, languages/ja_JP/LC_MESSAGES, languages/ja_JP, languages/el_GR/LC_MESSAGES/messages.mo, languages/el_GR/LC_MESSAGES, languages/el_GR, languages/fi_FI/LC_MESSAGES/messages.mo, languages/fi_FI/LC_MESSAGES, languages/fi_FI, languages/de_DE/LC_MESSAGES/messages.mo, languages/de_DE/LC_MESSAGES, languages/de_DE, languages/es_PE/LC_MESSAGES/messages.mo, languages/es_PE/LC_MESSAGES, languages/es_PE, languages/sv_SE/LC_MESSAGES/messages.mo, languages/sv_SE/LC_MESSAGES, languages/sv_SE, languages/cs_CZ/LC_MESSAGES/messages.mo, languages/cs_CZ/LC_MESSAGES, languages/cs_CZ, themes/venus/page_theme.php, themes/venus/full.php, themes/venus/js/jquery.pagepiling.js, themes/venus/js/html5.js, themes/venus/js/animatefunctions.js, themes/venus/js/selectivizr-min.js, themes/venus/js/custom.js, themes/venus/js/wow.min.js, themes/venus/js, themes/venus/home.php, themes/venus/css/main.less, themes/venus/css/bootstrap-modified.css, themes/venus/css/skeleton.css, themes/venus/css, themes/venus/grids/skeleton_grid.php, themes/venus/grids, themes/venus/animate.css, themes/venus/description.txt, themes/venus/default.php, themes/venus/view.php, themes/venus/sass/skeleton.scss, themes/venus/sass/_normalize.scss, themes/venus/sass, themes/venus/main.css, themes/venus/elements/footer.php, themes/venus/elements/header.php, themes/venus/elements, themes/venus/New folder, themes/venus/thumbnail.png, themes/venus
# concrete5 Cache Settings
Block Cache - Off
Overrides Cache - Off
Full Page Caching - Off
Full Page Cache Lifetime - Every 6 hours (default setting).
# Server Software
Apache/2.4.7
# Server API
cgi-fcgi
# PHP Version
5.6.23-2+deb.sury.org~trusty+1
# PHP Extensions
bcmath, calendar, cgi-fcgi, Core, ctype, curl, date, dom, ereg, exif, fileinfo, filter, ftp, gd, gettext, gmp, hash, iconv, json, libxml, mbstring, mhash, mysql, mysqli, mysqlnd, openssl, pcntl, pcre, PDO, pdo_mysql, Phar, posix, readline, Reflection, session, shmop, SimpleXML, sockets, SPL, standard, sysvmsg, sysvsem, sysvshm, tokenizer, wddx, xml, xmlreader, xmlwriter, xsl, Zend OPcache, zip, zlib
# PHP Settings
max_execution_time - 60
log_errors_max_len - 1024
max_file_uploads - 50
max_input_nesting_level - 64
max_input_time - 60
max_input_vars - 1000
memory_limit - 128M
post_max_size - 12M
sql.safe_mode - Off
upload_max_filesize - 24M
mysql.max_links - Unlimited
mysql.max_persistent - Unlimited
mysqli.max_links - Unlimited
mysqli.max_persistent - Unlimited
pcre.backtrack_limit - 1000000
pcre.recursion_limit - 100000
session.cache_limiter - <i>no value</i>
session.gc_maxlifetime - 7200
opcache.max_accelerated_files - 2000
opcache.max_file_size - 0
opcache.max_wasted_percentage - 5
I'm not sure how you're making changes, but it's possible your theme css or another block may be taking precedence. The only way to be sure is to open the debug console in your browser and inspect the h2 tag. It would help if you set the timeout on the slideshow to something wacky like 60,000 so you have a fighting chance of actually being able to view the rules that apply.
If that doesn't help, you can post a link to your site or PM me and I'll try to figure it out.